COVID-19: effects of the coronavirus on the brain
Various studies have shown that infection with the SARS-CoV-2 coronavirus and the disease it causes COVID-19 even effects on the brain may have, about by there blood vessels damaged will. Recent scientific research now has one Decrease in total brain mass detected in corona infected people.
The SARS-CoV-2 coronavirus not only affects the lungs and airways, but can also affect many organs of the human body. Numerous studies have shown that COVID-19 can affect the brain.
- According to scientific research, some SARS-CoV-2 infected people show a decrease in gray matter in the orbitofrontal cortex and a decrease in total brain mass.
- In these patients, the cognitive test results also deteriorated over time. It is not yet clear whether these changes are reversible.
- Another study showed an increased risk of dementia after contracting COVID-19 compared to other pneumonia.
COVID-19-associated abnormalities in brain structure
As the German Society for Neurology eV (DGN) in a current Message writes, several studies have already shown COVID-19-associated abnormalities in the brain structure. So far, however, it has remained unclear whether even milder courses of a SARS-CoV-2 infection can lead to such changes.
In the journal “Nature‘ a study has now been published which, as part of the large, longitudinal ‘UK Biobank Imaging Study“ was the first to study cerebral MRI changes in SARS-CoV-2 infected individuals for whom cerebral MRI was already available before the pandemic.
In the “UK Biobank Imaging Study” that began in 2006, more than 40,000 people (over 45 years of age) have since undergone multimodal cerebral MRI examinations of the brain in four centers according to standardized protocols.
The study was initially paused due to the pandemic; From February 2021, participants then began to be invited to another MRI scan. In the meantime, many of them had gone through a coronavirus infection.
Minimizing misinterpretations
To investigate the potential impact of SARS-CoV-2 infection on brain structure, the two scans (before and after COVID-19) were compared to non-COVID-19 participants.
The availability of pre-infection imaging minimized the likelihood that unknown pre-existing risk factors or abnormalities would later be misinterpreted as COVID-19 related. Participants with incidental cerebral findings on the first scan were excluded from the study.
There were no significant differences in the subjects’ age, gender, ethnicity, mean blood pressure, diabetes mellitus, weight/BMI, alcohol and nicotine consumption, or socioeconomic status.
Of 785 eligible subjects in the biobank (age 51-81) each with two cerebral MRI scans, 401 subjects had suffered SARS-CoV-2 infection between the two scans and 15 of them had been hospitalized. There was an average of 141 days between the infection diagnosis and the second scan.
The control group included 384 people. The mean interval between the two brain scans in the two groups was 3.2 ± 1.6 years.
Significantly more deteriorations in cognitive tests
The result showed significant longitudinal effects or MRI changes in the group of people who had been infected with SARS-CoV-2 in the meantime.
These included a decrease in gray matter, as well as a decrease in tissue contrast in the orbitofrontal cortex (brain cortex at the front of the eye sockets) and what is known as the parahippocampal gyrus (part of the limbic system located in the temporal lobe).
Tissue changes or damage were also found in brain regions that are functionally connected to the primary olfactory cortex, as well as a greater decrease in total brain mass. In cognitive tests, too, those who had been infected with SARS-CoV-2 in the meantime showed significantly more deterioration (in the time between the two scans) than those who were not infected.
The longitudinal group differences (in imaging and cognition) persisted even when the 15 participants hospitalized for COVID-19 were not included in the statistics.
The pathomechanism of SARS-CoV-2-associated brain changes must now be further researched. The scientists discuss the spread of the virus via olfactory-neural pathways and inflammatory processes.
The authors of the study believe that the loss of sensory-olfactory input due to the loss of the sense of smell (anosmia) could also have indirectly caused structural changes.
“The data from the UK Biobank show that there is a morphological correlate for the neurological post-COVID symptoms,” comments DGN Secretary General Prof. Dr. medical Peter Berlit. “Whether the changes documented in the imaging are reversible over time or persist in the long term in the sense of neurodegeneration must now be investigated further in the follow-up.”
Significantly higher risk of dementia
Another, on the open access repository Europe PubMed Central (Europe PMC) published study also describes COVID-19-associated functional cerebral changes. Here, however, the more than 10,000 people affected all had severe SARS-CoV-2 pneumonia.
Three percent developed new dementia after more than 30 days. In this study, the risk of dementia after SARS-CoV-2 pneumonia was 30 percent higher than for non-COVID-19-associated pneumonia.
Patients with documented pre-existing symptoms of dementia or cognitive deficits were excluded. Comorbidities that can increase the risk of developing dementia were taken into account in the multivariate analysis (e.g. high blood pressure, drug, nicotine and alcohol consumption, certain neurological and psychiatric diseases).
“The data show that the virus, albeit fortunately only in rare cases, can also lead to long-term changes in the brain. Against this background, the vaccination not only offers protection against severe acute courses of the infection, but also against consequential damage,” says Berlit. (ad)
Author and source information
This text corresponds to the specifications of medical specialist literature, medical guidelines and current studies and has been checked by medical professionals.
Swell:
- German Society for Neurology eV: SARS-CoV2-associated changes in the brain structure in the long-term in non-hospitalized persons, (accessed: March 19, 2022), German Society for Neurology eV
- Douaud G, Lee S, Alfaro-Almagro F et al.: SARS-CoV-2 is associated with changes in brain structure in UK Biobank; in: Nature, (veröffentlicht: 07.03.2022), Nature
- UK Biobank: Imaging Study, (Abruf: 19.03.2022), UK Biobank
- Qureshi AI, Baskett WI, Huang W et al.: New Onset Dementia Among Survivors of Pneumonia Associated with Severe Acute Respiratory Syndrome Coronavirus 2 Infection; in: Europe PMC, (veröffentlicht: 07.03.2022), Europe PMC
Important NOTE:
This article contains general advice only and should not be used for self-diagnosis or treatment. He can not substitute a visit at the doctor.